When Fourth Nattawat, a successful CEO, is tasked with fulfilling a promise his late grandfather made years ago, he finds himself bound by duty to marry Gemini, a man he's never met. Gemini, who has faced hardships all his life, is suddenly thrust into a marriage he never expected, with a man he doesn't know. As they navigate their new life together, the promise that once seemed like a burden slowly turns into something deeper. Through love, sacrifice, and unexpected moments of connection, Gemini and Fourth discover that sometimes the most beautiful things grow from the promises we make.